1. Field of the Invention
This invention relates to a plasma display device and a driving method for a plasma display panel (PDP). More specifically, the present invention relates to a device and method for applying a sustain discharge waveform to a scan electrode and a sustain electrode during a sustain period.
2. Discussion of the Background
A plasma display device displays characters or images using plasma generated by gas discharge, and the PDP may have several thousands to several millions of pixels arranged in the matrix format, depending on its size.
FIG. 1 is a partial perspective view showing a typical PDP, and FIG. 2 shows a typical PDP electrode arrangement.
As shown in FIG. 1, parallel pairs of a scan electrode 4 and a sustain electrode 5 are arranged on a substrate 1 and covered with a dielectric layer 2 and a protective layer 3. A plurality of address electrodes 8, which are covered with a dielectric layer 7, are arranged on a substrate 6. Barrier ribs 9, which are formed on the dielectric layer 7, are formed in parallel to, and in between, the address electrodes 8. A fluorescent material 10 is formed on the dielectric layer 7 and sides of the barrier ribs 9. The substrates 1 and 6 are joined together with a discharge space 11 formed therebetween, so that the scan electrodes 4 and the sustain electrodes 5 lie in a direction substantially perpendicular to the address electrodes 8. A portion of the discharge space at an intersection between an address electrode 8 and a pair of a scan electrode 4 and a sustain electrode 5 forms a discharge cell 12.
As shown in FIG. 2, the PDP comprises a matrix of m×n pixels. In detail, address electrodes A1 to Am are arranged in columns, and scan electrodes Y1 to Yn and sustain electrodes X1 to Xn are alternately arranged in rows.
A driving method for such a PDP may include dividing an image frame into a plurality of subfields, each of which may comprise a reset period, an address period, and a sustain period. During the reset period, discharge cell states are initialized to stably perform a subsequent addressing operation. The address period is for selecting cells to be turned on and accumulating wall charges on those turned-on cells (i.e., addressed cells). The sustain period is for performing a discharge to display an image on the PDP.
During the sustain period, a sustain discharge pulse may be alternately applied to the scan and sustain electrodes, and during the reset and address periods, reset and scan waveforms may be applied to the scan electrode. Therefore, a typical sustain electrode driving circuit may output a sustain discharge waveform, but a typical scan electrode driving circuit may output reset, scan, and sustain discharge waveforms. Hence, a circuit for outputting the reset and scan waveforms may be added to the scan electrode driving circuit. Thus, a sustain discharge waveform output path in a scan electrode driving circuit may be longer than in a sustain electrode driving circuit. Further, more parasitic components may exist in the scan driver's output path as compared to the sustain driver's output path, which results in the output paths having different impedance. Consequently, applying sustain discharge waveforms to the scan and sustain electrodes using different sustain discharge paths with different impedances may problematically result in different light waveforms.